Arrangement at vertically adjustable stands



Dec. 30, 1969 G. WIKLUND 3,486,583

7 ARRANGEMENT AT VERTICALLY ADJUSTABLE STANDS Filed Dec. 15, 1967 3 Sheets-Sheet 1 Fig.1

Dec. 30, 1969 a. WIKLUND I 3,486,533

ARRANGEMENT AT VERTIGALLY ADJUSTABLE STANDS Filed De c. 15, 1967 a Sheets-Sheet z Fig.3

Dec. 30, 1969 e. WIKLUNDY Fil d Dec). 15, 1967 ARRANGEMENT AT VERTIGALLY ADJUSTABLE STANDS 3 Sheets-Sheet 3 Tr T "LIL U12 :Iffffli: :r EJ- 3 United States Patent 3,486,583 ARRANGEMENT AT VERTICALLY ADJUSTABLE STANDS Georg Wiklund, Box 2539, Sundsvall, Sweden Filed Dec. 15, 1967, Ser. No. 690,834 Claims priority, application Sweden, Nov. 21, 1967, 15,984/ 67 Int. Cl. B661) 11/04; B661? 3/22; E04g 1/18 US. Cl. 187-18 4 Claims ABSTRACT OF THE DISCLOSURE A mobile stand which includes a platform and a pair of articulated systems of lifting arms on opposed sides of the platform for raising and lowering it, the systems of arms being interconnected by transverse shafts and the uppermost and lowermost central point being fixedto the platform and the stand, and includes stabilizing link systems transverse to the systems of lifting arms for preventing uneven movement during lifting and includes means for facilitating the initial lifting of the platform from its lowered position.

This invention relates to an arrangement at preferably mobile stands for cranes, hoists or the like, for example for building purposes, which stands are adapted to be raised and lowered and comprise a bottom frame mounted on a car or vehicle, and a plurality of platforms, balconies or the like adapted to be raised and lowered in relation to the bottom frame by a system of hinged arms of crosswise relationship and articulated with one another so as to form an extendible shears mechanism.

In a known embodiment of this type the system of cross-connected hinged arms is constructed as a simple shears, one of the lowermost hinged arms being articulated at the bottom frame, and the other lowermost hinged arm running by rolls on bars mounted in the frame and being adapted to be actuated by some power means for displacement in the longitudinal direction of the frame, thereby raising or lowering the stand.

An arrangement of the aforesaid type involves several disadvantages. When the stand upon the application of a force on the end of one hinged arm is being raised, great breaking loads will develop in the hinged arms and in the links by which the hinged arms are united. Thereby the size of the stand and its capacity are already at the raising operation to carry a load, for example a building crane, building material or the like are limited. Moreover, much power is required for raising the stand.

The said disadvantages are eliminated in that the uppermost and lowermost central links of the carrying shears systems are stationarily connected with the platform and the bottom frame, respectively, and that the outermost link ends of the shears systems in the same plane are provided with rolls to roll in horizontal, upwardly and downwardly defined grooves in the platform and the bottom frame, respectively, said rolls carrying with them locking bars which are provided with holes corresponding to other holes in the bottom frame for securing the stand in a certain height position. According to one embodiment the stabilization of the stand is improved by a system of stabilizing links connecting the ends of the two carrying link systems with each other, in such a manner, that the ends of the carrying links are slidably mounted on the outer shafts between the ends of the links in the carrying link systems, the ends of the lowermost carrying links being guided in parallel by a parallel construction in the bottom frame. For facilitating the initial lifting phase, there is further mounted in the bottom frame a lift starting device by which the links in the "ice carrying link systems are lifted apart some distance before the main lifting force is being applied.

The invention is described in greater detail in the following, with reference to the accompanying drawings showing embodiments of the invention.

FIG. 1 shows in a lateral view a stand according to the invention mounted on a vehicle.

FIG. 2 shows a partial section along the longitudinal central line through the vehicle and the stand.

FIG. 3 shows a front view of the uppermost part of a longitudinal stabilizing link system according to the invention.

FIG. 4 shows in a horizontal view, partly in section, the lower part of the carrying link system with the parallel construction according to the invention.

FIG. 5 shows a side view, partly in section, of the lower part of a carrying link system with the lift starting device according to the invention.

The arrangement comprises a bottom frame 1 adapted to be mounted on a vehicle, which in the embodiment shown (FIG. 1) is a truck. On each side of said frame 1 are articulated in the same stationary point 4 a carrying system of hinged arms which are placed crosswise and articulated with each other so as to form a shears, of which hinged arms the lowermost arms are half as long as the remaining arms and designated by 2 and 3. To this system is connected symmetrically a similar carrying system of hingedarms joined to form a shears, of which arms the lowermost ones are designated by 5 and 6. Both of said systems are articulated with one another in the centre of the hinged arms and at their points of intersection. In this way a double carrying shears system is obtained on every frame side, which systems are in parallel with each other. The ends of the hinged arms 5 and 6 can be displaced in the bottom frame by rolls 7 running in grooves formed by the bottom frame beams. At the axles of the rolls 7 skid bars 9 are mounted, which are provided with conical locking holes 8. The bars are guided in pathways in the bottom frame, and their locking holes can be engaged by a conical locking pin 20 screwed into the frame, and thereby secured the stand in the lifted position. The two carrying systems, each on its side of the frame 1, are connected by shafts 10 at the ends of iheklinks and by shafts 11 at the central points of the in s. For raising and lowering the stand, two hydraulic cylinders 12, for example, can be applied, one cylinder on each side, which cylinders engage with the lowermost movable central shaft 11 in the stand. Thereby, a symmetric load on the stand is obtained and breaks in the stand are prevented. For a stand mounted on a vehicle the hydraulic cylinders can be driven in an easy way from the hydraulic system of the vehicle. The raising and lowermg operations also may be effected by pairs of square thread screws (not shown) which may be driven from the auxiliary drive of the vehicle, for example via gears and chains. The hydraulic cylinders of the screws also may be arranged lying and to engage with the lowermost end shafts 10.

At the uppermost central shaft 11 of the carrying link systems a platform 14 is mounted, in such a manner, that the ends of the uppermost carrying links by rolls 7 can be displaced in horizontal grooves in the lower surface of the platform, similar to the construction at the bottom frame 1.

When the stand has reached its maximum height, an overflow valve is opened whereby the outward movement of the piston rods of the hydraulic cylinders 12 is stopped. If the driving is effected by screws, a limit switch, for example, may be provided. In the case of hydraulic operation the hydraulic cylinders may be provided with built-in throttle washers, for preventing the stand from collapsing too fast, for example due to a possible oil leakage. In raised position, thus, the stand is supported on the four rolls 7 in the bottom frame 1 and also on the piston ends of the lift cylinders 12, and it is secured by the locking pins 20 at the same time as the energy supply to the hydraulic cylinders is stopped, for example by stop valves. By this arrangement, the stand is given a very firm support and it may be loaded with cranes and other loads with overhang, to the extent as permitted by the underlying vehicle or car, without being affected in its stability. The vehicle preferably is provided with supporting legs 19 for permitting a crane or a load to have a greater overhang.

The stand described, with a working platform 14, can be extended to a substantial height, for example eight meters or more, and with very good stability. It was found, however, particularly at great heights and when being exposed to heavy lopsided loads, that the stand has the tendency of sinking somewhat on one side or the other, which has its reason in the necessary play of the individual links and, of course, also in the position of the carrier vehicle. The small settlement which normally may take place, is not alarming per se, but it can irritate the person staying on the platform.

The said stand, further, has proved to require a tremendous initial lifting force, while after the very first separation of the links the power demand is substantially less. This is due to the fact, that the links are in a substantially horizontal position when the lifting forces of the lifting jacks are being transferred to the stand, and as the forces are distributed via the links, the horizontal components of the lifting forces, which components only produce a bending stress in the links, are of a considerable magnitude compared with the vertical force components or the real lifting forces. It is, therefore, essential to separate the individual links as soon as possible, so that the power distribution is made more favourable.

The present invention has as its object to eliminate the aforesaid shortcomings and to stabilize the stand still more as well as to facilitate the lifting.

The invention is characterized by a stabilizing link system which connects the two ends of the parallel carrying link systems with each other, a parallel construction for guiding the lower ends of the carrying link systems, and a lift starting device for applying a lifting force to a central shaft between the carrying link systems, which shaft it located at a greater height than the lowermost central shaft.

It appears from FIG. 3, that an embodiment of the stabilizing link system according to the invention comprises links 24 pivoted in pairs at their mutual central points 29, the ends of said links being slidably mounted by bushings 25 on the end shafts mounted in theends of the links of the carrying link systems. For ensuring that the stabilizing links 24 move simultaneously and the same distance relative one another, supporting links 27 are articulated both at the links 24 in the middle between their common pivotal point 29 and the ends, and at a bushing 28 mounted in the centre of the end shafts.

By this arrangement any change in level of one end of one carrying link system in relation to the corresponding end of the other carrying link system is effectively prevented, because such a change in level immediately results in the displacement of one or several of the link ends of the stabilizing link system. Thereby either a corresponding adjustment on the opposite side of the stabilizing link system is effected or the original level is maintained, in that the change is counteracted by the system.

FIG. 4 shows a horizontal view of the parallel construction at the lower ends of the carrying link systems. The parallel construction comprises the lowermost end shaft 30 which connects the two ends on the lowermost carrying links 31 extending in the same direction. The end shafts 30 are rigidly connected each with its guide beam 3-2 which 4 is slidably guided in holes, by a transverse beam 33, preferably that beam which supports the jacks 12.

It was found formerly that the roll of one of the carrying links 31 readily falls behind in the case of lopsidedness, whereby one side of the stand is made to be located lower than the other side. By the arrangement according to the invention, the two rolls 35 mounted at the same end of the carrying link systems so are guided, that they simultaneously roll forward or backward. As, thus, the links are moved in parallel, lopsided raising or lowering of the stand is prevented.

FIG. 5 shows a front view, partly in section, of a stand provided with the lift starting device according to the present invention. It appears from this figure, that the two carrying link systems are connected with transverse central shafts, for example 11, 36. In the main construction a lifting force is applied to the lowermost beam 11 whereby the stand is caused to unfold upwardly. In view of the load on the working platform which in many cases is of a substantial magnitude, for example a hoisting crane, machines or the like, the jacks 12 for the lifting must exercise a tremendous initial force for moving the stand from the totally collapsed position to a somewhat raised position. Thanks to the fact that the links are separated a small distance, the lifting force required is considerably smaller.

In order to reduce the demand of initial force, according to the invention a first lifting force is applied against the next to lowermost shaft 36 of the said central shafts with the assistance of a lift starting device. This device comprises a sleeve detachably mounted on the projecting end of the jack pistons. This sleeve, which in the following is called cap 37, is at one of its ends provided with a bottom and at its other end with a radially projecting flange 38. The lowermost central shaft 11, which preferably comprises two parallel U-beams, support an annular guide bushing for the cap 37, in such a manner that the flange 38 of the cap is stopped by the underside of the guide bushing and the shaft 11. The lift starting device according to the invention operates as follows. When the stand is to be raised, pressure fluid is applied to the jacks 12, so that their pistons move vertically upwards. Thereby the cap 37 is moved upwardly through the guide bushing against the next to lowermost shaft 36, and a lifting force is applied thereon before the lowermost shaft 11 is being actuated. The cap 37 is of such a length, that the next to lowermost shaft 36 can be lifted a certain distance, so that the lower carrying links are separated somewhat before the flange 38 is stopped against the lowermost shaft 11, whereby also this shaft is lifted upwardly.

By applying the lifting force to a shaft located higher up in the stand, the power demand in the jacks 12 is reduced as well as there will be less stress in the links as Well as in the lift starting device.

In the same way, when the stand is being lowered, the very last collapsing movement for the link systems will be softer than previously.

A hoist crane can be mounted in a carriage 0n the working platform 14, whereby the stand together with the crane can be employed as a building crane for new constructions. A crane of this type is equivalent to a conventional smaller tower crane and can be operated in the same way from the platform or by remote control from the building site. It offers in addition the advan tage, that the expensive and time-consuming mounting and dismounting work for conventional building cranes is eliminated and that the crane is not bound for a certain time to a definite place. Compared with usual mobile cranes, which always are operated from the ground, it offers the advantage that the crane operator can operate from the platform and, thus, always has a free view.

Another way of employing the stand according to the invention is to utilize it as a vertically adjustable working platform, i.e. without a crane. There are a number 5. of applications of this type, for example scaling of roofs, particularly at varying roof heights, plastering, sizing, washing and painting, whereby the raising and lowering of the platform can be effected from the platform, also in combination with a simultaneous movement of the vehicle. This type of stand, thus, is employed indoors of large industrial buildings, in rock chambers and the like.

For operations to be carried under the roof, for example pipe laying and electric installations, the same carriage which is used for the crane can be utilized for the mounting of various tools, for example a pair of forks adapted to be turned by the carriage. When the stand is in its lowered position, pipe ducts or other details are placed in the forks, whereafter the stand is raised at the same time as the carriage is turned for fitting the pipe or details in position. If so required, the stand may thereby also be used for securing the workpiece by pressing. In this case, thus, the stand serves as a hoist.

The constructions shown can be modified in several ways without abandoning the object of the invention. Besides the described change in the operation of raising and lowering the stand, the balconies can be provided with projecting decks for improving the accessibility at different working places, for example niches, protrusions or the like, and as mentioned, hoists and the like may be mounted on the balconies. In the hinged arms of the shears system electric lines may be laid which at the height of the balconies are provided with taps for light, power supply etc. An arrangement as described may also be utilized for transporting material to a working place, and after its arrival there be employed as a hoist to the desired level.

The invention shown and described by way of examples is, however, not restricted thereto, but can be applied in many different ways and modified within the scope of the inventive idea.

What I claim is:

1. A mobile building stand having a base and a platform adapted to be raised and lowered, two articulated systems of lifting arms disposed on opposed sides of said stand and transverse shafts interconnecting the opposed lifting arms at points of intersection, the improvement comprising means securing the central uppermost and lowermost lifting arms to the platform and base respectively, rollers provided at the outermost ends of the upper and lower arms of said systems, the platform and base being provided with horizontal grooves to receive said rollers, locking bars moveable with said rollers, means for locking said 'bars in a desired position on said base, two stabilizing link systems on opposed sides of said stand and mounted transversely to the lifting arms systems, each link system comprising links articulated in pairs at their central points, the ends of said links being slidably mounted on the ends of said transverse shafts adjacent said lifting arms, supporting links articulated with the centre of said said transverse shafts and with the stabilizing links at the midpoint between the central pivotal point and the ends thereof, and means for raising said plaftorm.

2. A mobile building stand having a base and a platform adapted to be raised and lowered, two articulated systems of lifting arms disposed on opposed sides of said stand and transverse shafts interconnecting the opposed lifting arms at points of intersection, the improvement comprising means securing the central uppermost and lowermost lifting arms to the platform and base respectively, rollers provided at the outermost ends of the upper and lower arms of said systems, the platform and base being provided with horizontal grooves to receive said rollers, locking bars moveable with said rollers, means for locking said bars in a desired position on said base, two stabilizing link systems mounted on opposed sides of said stand and transversely of said lifting arms systems, said link systems being articulated with the ends of said arms, and means for facilitating the initial lifting-of said platform comprising a plurality of jacks, elongated caps atop each jack, said caps being provided with radial flanges at the lower ends thereof, said lowermost central transverse shaft being provided with vertical guide holes therethrough to receive said elongated caps, whereby said caps when raised by said jacks will exert a lifting force on the next to lowermost transverse shaft before said flange will exert force on the lowermost transverse shaft.

3. A mobile building stand as claimed in claim 1 wherein the means for raising the platform includes means for exerting a lifting force on the next to lowermost transverse shaft before exerting a lifting force on the lower-most transverse shaft.

4. A mobile building stand as claimed in claim 1 and further comprising at least one longitudinal guide beam rigidly connected to one of the lowermost transverse shafts and extending toward the centre of said stand and a trans verse central beam having guide means for slid-ably receiving and guiding said longitudinal guide beam.

References Cited UNITED STATES PATENTS 722,166 3/1903 Taft 187-18 3,174,722 3/1965 Alm 18718 3,373,844- 3/ 1968 Schafer 182141 FOREIGN PATENTS 545,141 2/ 1956 Belgium.

HARVEY C. HORNSBY, Primary Examiner US. Cl. X.R. 182-141; 254-122 

